Hinge assemblies are widely used in foldable electronic devices such as mobile phones and electronic notebooks. These foldable electronic devices typically include two housings. Normally, one of the housings called a main body contains most of the electronic elements of the foldable electronic device. The other housing called a cover contains fewer or even no electronic elements. The hinge assembly is used to interconnect the main body and the cover, and to enable the cover to be foldable relative to the main body.
One kind of hinge mechanism is illustrated in FIG. 5. The hinge mechanism 500 includes: a cam 510, having a wedge-shaped portion 512 on one end thereof, and an engaging portion 514 on the other end thereof which is used for engaging with a cover of a foldable mobile phone; a corresponding cam follower 520 having two jaws 522; and a spring 530 for pressing the cam follower 520 to urge against the cam 510. The cam 510, the cam follower 520 and the spring 530 are received in a hinge housing 540, which is, in turn, covered by a hinge cover 550. The hinge housing 540 and hinge cover 550 are engaged with a body of the foldable mobile phone. In use, the wedge-shaped portion 512 moves along the jaws 522. The cam 510 together with the cover rotates relative to the body of the foldable mobile phone in a predetermined direction. However, the range of rotation of the cover is limited. In addition, the rotation of the hinge mechanism is unstable.
What is needed, therefore, is a hinge assembly which is capable of providing a wide range of rotation and stable rotation.